SSL scans showing up in the log / 2022-11-18

A comment on irc made me have a look at the logs for my haproxy system to get an idea whether any weird vulnerability scan came by. No special vulnerability scan showed up, but my attention was drawn to a number of lines like:

Nov 18 08:05:01 wozniak haproxy[13987]: 2001:470:1:332::28:37618 [18/Nov/2022:08:05:01.900] https-in/1: SSL handshake failure
Nov 18 08:05:44 wozniak haproxy[13987]: 2001:470:1:332::28:27286 [18/Nov/2022:08:05:44.328] https-in/1: SSL handshake failure
Nov 18 08:06:22 wozniak haproxy[13987]: 2001:470:1:332::2e:3137 [18/Nov/2022:08:06:21.962] https-in/1: SSL handshake failure
Nov 18 08:06:22 wozniak haproxy[13987]: 2001:470:1:332::2d:33085 [18/Nov/2022:08:06:22.278] https-in/1: SSL handshake failure
Nov 18 08:06:22 wozniak haproxy[13987]: 2001:470:1:332::2d:17531 [18/Nov/2022:08:06:22.593] https-in/1: SSL handshake failure
Nov 18 08:06:22 wozniak haproxy[13987]: 2001:470:1:332::30:58869 [18/Nov/2022:08:06:22.915] https-in/1: SSL handshake failure
Nov 18 08:06:23 wozniak haproxy[13987]: 2001:470:1:332::2e:46537 [18/Nov/2022:08:06:23.228] https-in/1: SSL handshake failure
Nov 18 08:06:23 wozniak haproxy[13987]: 2001:470:1:332::29:20027 [18/Nov/2022:08:06:23.544] https-in/1: SSL handshake failure
Nov 18 08:06:24 wozniak haproxy[13987]: 2001:470:1:332::31:13423 [18/Nov/2022:08:06:23.872] https-in/1: SSL handshake failure
Nov 18 08:06:24 wozniak haproxy[13987]: 2001:470:1:332::28:56683 [18/Nov/2022:08:06:24.197] https-in/1: SSL handshake failure
Nov 18 08:06:24 wozniak haproxy[13987]: 2001:470:1:332::31:5055 [18/Nov/2022:08:06:24.524] https-in/1: SSL handshake failure
Nov 18 08:06:24 wozniak haproxy[13987]: 2001:470:1:332::2e:20907 [18/Nov/2022:08:06:24.841] https-in/1: SSL handshake failure

If there is one of two of these lines from one address, it is a sign of a client which can't finish the SSL negotiation. With my site that probably means and old client which doesn't understand LetsEncrypt certificates without an extra certification path.

But this is quote a number of SSL errors from the same IPv6 range in a short time. I wondered what was behind this and did a bit of testing, until I found it's simple to cause this by doing an SSL test. For example with the famous Qualys SSL test or with an ssl scan tool. This is logical: ssltest uses a lot of different negotiations to test what actually works.